Question

in C lets say I declare

long long x = 123456789012345

and then I do

x / pow(10, 13) == 12

This evaluates to false rather than the expected true. What am I missing?

Answer 1

it does work however if I do

int y = x / pow(10, 13)

and then

y == 12

This does evaluate to true

Answer 2

I know this is a bit late, but it might be useful to know.

In your code:
long long x = 123456789012345

The right side of the expression is evaluated by the compiler as an integer before it is assigned to the long, meaning the value overflows.

This is why the second check works but not the first.
To make the compiler interpret the value as a long, you need to specify that with a capital L, like so:
long x = 123456789012345L
or
long long x = 123456789012345LL